1. Field
One embodiment of the invention relates to a coil assembly used in a disk device having a disk for use as a recording medium, a head suspension assembly provided with the coil assembly, a disk device, and a method of manufacturing a head suspension assembly.
2. Description of the Related Art
In recent years, disk devices, such as magnetic disk devices, optical disk devices, etc., have been widely used as external recording devices of computers or image recording devices.
A disk device, e.g., a magnetic disk device, generally comprises a magnetic disk, a spindle motor that supports and rotates the disk, a head actuator that supports a magnetic head, a voice coil motor for driving the head actuator, a circuit board unit, etc., which are arranged in a case
The head actuator includes a bearing portion attached to the case and a plurality of arms stacked on and extending from the bearing portion. A magnetic head is attached to each arm by means of a suspension. The circuit board unit is formed integrally having a base portion and a main flexible printed circuit board (hereinafter, referred to as a main FPC). A head IC, connector, etc. are mounted on the circuit board unit. The main FPC extends close to the bearing portion from the base portion. An extended end portion of the main FPC includes a plurality of connecting portions. Each connecting portion is provided with a plurality of connection pads and a through hole through which a screw is passed. The connecting portion is fastened to the bearing portion of the head actuator by the screw that is passed through the through hole.
Further, a relay flexible printed circuit board (relay FPC) is fixed on each arm and each suspension of the head actuator. One end of the relay FPC is connected to the magnetic head, while the other end is connected to its corresponding connecting portion of the main FPC. The other end of each relay FPC is provided with a plurality of connection pads. As these connection pads are soldered individually to the connection pads of each connecting portion of the main FPC, the relay FPC and the main FPC are connected electrically and mechanically to each other. The magnetic head supported on each suspension is connected electrically to the circuit board unit through the relay FPC and the main FPC.
When the magnetic disk is rotating, in the magnetic disk device constructed in this manner, the magnetic head is moved to and located in a desired radial position on the disk, that is, on a desired track, by the head actuator. Information is written to and read from the disk by the head.
Recently, with the miniaturization of disk devices, individual components, such as head actuators, have been reduced in size. For the small-sized head actuators of this type, it is hard to secure a space in which connecting portions of a main FPC are screwed to a bearing portion. Besides, a space for connection work is too narrow to ensure high operating efficiency. Proposed in Jpn. Pat. Appln. KOKAI Publication No. 10-092125, therefore, is a method in which connecting portions of a main FPC are fixed by being interposed in a bearing portion of a head actuator without using screws, for example. According to this method, however, the connecting portions of the main FPC and connecting portions of a relay FPC must be soldered to one another, so that the connection work is troublesome and requires skill.
Proposed in Jpn. Pat. Appln. KOKAI Publication No. 2001-143246, for example, is a head actuator in which connecting portions of a main FPC and connecting portions of a relay FPC are joined together at a junction between a suspension and an arm, and they are pressure-bonded together by fixing a fixing plate to them by caulking from above.
Normally, the connecting portions of the main FPC extend in opposite directions from the opposite sides of an extended end of the main FPC. These connecting portions are bent at right angles and connected to the relay FPC. Described in Jpn. Pat. Appln. KOKAI Publication No. 2002-245732 is an arrangement in which an arm is assembled to a bearing portion after connecting portions of a main FPC are previously soldered to connection wiring on a suspension.
According to the head actuator described in Jpn. Pat. Appln. KOKAI Publication No. 2001-143246, the main FPC and the relay FPC need not be soldered to each other. It is difficult, however, to align the connecting portions accurately with one another, so that the reliability lowers. Since the fixing plate is fixed by caulking, moreover, disassembling the junction is too hard to repair the head actuator with ease.
According to the head actuator described in Jpn. Pat. Appln. KOKAI Publication No. 2002-245732, operation is troublesome because two arms and suspensions on which magnetic heads are mounted must be handled together with a board unit that has the main FPC. It is hard to make a space between the connecting portions that extend in the opposite directions from the main FPC narrower than the width of the main FPC, which hinders miniaturization of the head actuator.